This invention relates to an intraocular anterior chamber implant.
Intraocular anterior chamber implants have been developed over the last twenty five years and are primarily used for the correction of aphakia.
Such intraocular implants include an optic portion which acts as a lens so as to perform the function of the lens of the eye which has been removed and a haptic portion by means of which the implant is held in position.
It was found some years ago that a very desirable material for such an intraocular anterior chamber implant is polymethylmethacrylate usually known as PMMA and sold in clinical quality under the Trade Mark "Perspex CQ". It has been found that an implant made of this material which is properly held in position can be tolerated by the eye.
I proposed some years ago the use of an intraocular anterior chamber implant comprising an optic integral with a haptic which includes two pairs of feet projecting in opposite directions away from the optic. Such an intraocular anterior chamber implant is illustrated in FIGS. 1 and 2 in which the optic is indicated at 1 and is biconvex. The haptic consists of two pairs of feet 2 and 3 projecting from opposite sides of the optic from a part frusto-conical ledge 4. Each foot is shown with a circular hole 5 which may be omitted.
While implants of the type illustrated in FIGS. 1 and 2 have met with considerable success, the need remained for further improvement in the design. In particular such implants have been used successfully only in widths of 6 or 7 mm, requiring incisions of 7 or 8 mm respectively for their insertion. It is often highly desirable to make use of a narrower implant, e.g. one which is only 5 mm or even 4 mm wide. An obvious advantage of using a narrower implant is the reduction in the incision needed for its insertion to 6 mm or even 5 mm. A narrow implant is desirable when the eye into which it is to be inserted is relatively small. Moreover a narrow implant is particularly desirable when it is to be inserted into an eye from which a cataract has been extracted. In such cases the secondary implantation is normally performed after the eye has recovered from the phacoemulsification or allied procedure used for the cataract extraction.
Despite the need for narrower implants, no design heretofore known has been suitable for providing an implant having a width of 5 mm or less which is stable in use, i.e. has no tendency to move after it has been inserted in position and does not damage or iritate tissues and surfaces with which it comes into contact. In particular attempts to merely scale down the implant design of FIGS. 1 and 2 to produce an implant 5 mm or less wide, as well as attempts to file down a 6 mm wide implant to produce the desired narrower one have not been found to yield a stable implant.